Add monochrome_apk_checker to kitkat waterfall.

The fact that it isn't running appears to have been an oversight.

Bug: 1029936
Change-Id: I4c70311bca05f2088fd0e99112512a015524bd95
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1946875
Commit-Queue: Erik Chen <erikchen@chromium.org>
Commit-Queue: John Budorick <jbudorick@chromium.org>
Auto-Submit: Erik Chen <erikchen@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720719}

testing/buildbot/chromium.android.json

@@ -4958,6 +4958,27 @@
         },
         "test": "wtf_unittests"
       }
+    ],
+    "isolated_scripts": [
+      {
+        "isolate_name": "monochrome_apk_checker",
+        "merge": {
+          "args": [],
+          "script": "//testing/merge_scripts/standard_isolated_script_merge.py"
+        },
+        "name": "monochrome_apk_checker",
+        "swarming": {
+          "can_use_on_swarming_builders": true,
+          "dimension_sets": [
+            {
+              "device_os": "KTU84P",
+              "device_os_type": "userdebug",
+              "device_type": "hammerhead",
+              "os": "Android"
+            }
+          ]
+        }
+      }
     ]
   },
   "KitKat Tablet Tester": {

testing/buildbot/waterfalls.pyl

@@ -340,6 +340,7 @@
         ],
         'test_suites': {
           'gtest_tests': 'chromium_android_gtests',
+          'isolated_scripts': 'monochrome_apk_checker_isolated_script',
         },
         'os_type': 'android',
       },